1. Field of the Invention
One embodiment of the present invention relates to a method for driving an input-output device. Further, one embodiment of the present invention relates to an input-output device.
2. Description of the Related Art
In recent years, techniques of devices from which data is output and to which data is input by incidence of light (such devices are also referred to as input-output devices) have been developed.
As an input-output device, there is an input-output device which includes a plurality of photodetectors (also referred to as optical sensors) arranged in matrix in a pixel portion and a backlight including light-emitting diodes with a plurality of colors as light sources (for example, Reference 1). In the input-output device disclosed in Reference 1, in each frame period, the backlight is lit while the colors of emitted light are switched so that full-color images are displayed, and light reflected by an object is read as data. Thus, the input-output device disclosed in Reference 1 functions as a touch panel. Note that a method by which a backlight is lit while the colors of emitted light are switched in each frame period is also referred to as a field-sequential method.